Renata wins a $20 gift card to an online music site. after renata purchases 16 songs, the gift card has a remaining balance of $0. which equation represents the relationship between y, the remaining balance on renata’s gift card, and x, the number of songs purchased?

Well we can use $ left as the y axis and the amount songs purchased as the x axis.  First we are going to divide 20 by 16 to get 1.25 which means that each song is $1.25. *Which means after 16 songs on the x axis the lone should be at the bottom at point (0, 0).*  Your equation is y=20-1.25x If you need more information just let me know :)